The false warning went out just before 7 p.m. in the evening, through broadcaster NHK's Japanese mobile app and website. It was corrected less than 10 minutes later.

NHK has apologized, adding that there are no reports of problems caused by the mistake. The broadcaster blames a "switching error," without elaborating.

An NHK spokesperson told Reuters that the broadcaster is "still checking" on the cause.

Early Saturday morning, people in Hawaii received the following push notification: "BALLISTIC MISSILE THREAT INBOUND TO HAWAII. SEEK IMMEDIATE SHELTER. THIS IS NOT A DRILL."

It took another 38 minutes for the Hawaii Emergency Management Agency to send an additional message that the message was a false alarm.

"Our focus has been getting the notification out to the public," said Vern Miyagi, the administrator of Hawaii's Emergency Management Agency, as NPR's Colin Dwyer reported. "One thing that we have to work on more is the cancellation notice in this event."

Both Hawaii and Japan have been increasingly concerned about North Korea's continued weapons testing.